Insulator insert for thermal sensing device



Feb. 28, 1967 M. J. CAPARONE INSULATOR INSERT FOR THERMAL SENSING DEVICE Filed July 11, 1963 2 Sheets-Sheet 1 c Q i Feb. 28, 1967 M. J. CAPARONE 3,306,109

INSULATOR INSERT FOR THERMAL SENSING DEVICE Filed July 11, 1965 2 Sheets-Sheet 2 United States Patent tion of Delaware Filed July 11, 1963, Ser. No. 294,350

6 Claims. (Cl.

This invention relates to hot water heater controls and more particularly to an insulator insert used on a hot water heater thermostat.

One of the major problems facing manufacturers of hot water heaters resides in corrosion. In recent years, manufacturers have substantially prolonged the life of hot water heaters by lining the tanks of the heaters with glass and other similar ceramic materials. This lining has greatly diminished corrosion in tanks; however, it has aggravated the problem of galvanic corrosion which results from the use of dissimilar metals in the presence of an electrolyte. A material such as copper, brass or bronze, for example, causes less noble metals to sacrifice themselves to the copper, brass, or bronze materials through the medium of the electrolyte, which in the case of a hot water heater, is in the Water in the tank. In combatting galvanic corrosion, attempts have been made to protect components exposed to the water against such the water in the tank greatly Since copper, the electromoposition in the electromotive series. Another approach is to provide a plastic coating or sleeve to isolate the more noble metals, such as copper, brass or bronze, which thermore,

cavity of the shank while leaving the exterior thereof free of the coating such that threads may be formed thereon.

Accordingly, an object of this invention is to provide an insulator insert for hot water heater controls which will reduce tank corrosion and prolong tank life.

of its higher- Another object of this invention is to provide an insulator insert for hot water heater controls. which does not reduce the amount of sensitivity of the rod and tube. One feature of this invention is to provide an insert which will be readily retained upon the shank assembly of the hot water heater control by existing components currently used in a great majority of the controls.

Another feature of the present invention is an insulator with such configuration that the great majority of the shank is covered and insulated from causing galvanic action.

Another object of the present invention is to increase the resistance to galvanic action within a hot water heater tank to prolong life of a sacrificial anode and thereby lengthen the useful life of the tank.

The above problems have been overcome by the use of the present invention which in its broadest aspect is an insulator insert for use on a hot water heater thermostat shank assembly with a cylindrical cavity formed in the shank and a rod and tube assembly mounted within the cavity. The insert includes a body portion which excavity for shielding the shank from galvanic action and a device for interlocking the insert with a plastic tube encased on the rod is used for the mechanical interlock.

Other features and advantages not specifically enumerated above will be apparent after considering the following detailed description and the appended claims. The preferred form which the invention may assume is illustrated in the accompanying drawings in which:

FIGURE 1 is a vertical cross-section of a conventional hot water heater having a thermostat in its lower portion utilizing the present invention;

FIGURE 2 is an enlarged perspective view of a detail shown in FIG. 4;

FIGURE 3 is an end view of FIG. 2;

FIGURE 4 is a partial vertical cross-section of a hot water control extending into a conventional hot water heater .and having a shank assembly with the present invention mounted thereon;

FIGURE 5 is an enlarged fragmentary vertical crosssectional view of the present invention as illustrated in FIGURE 4;

FIGURE 6 is a fragmentary vertical cross-sectional view of another embodiment of the present invention mounted on a conventional shank assembly of a hot Water thermostat;

FIGURE 7 is an tail shown in FIG. 6;

FIGURE 8 is an end elevation of the embodiment of the present invention illustrated in FIGURE 7;

FIGURE 9 is a fragmentary sectional view showing another embodiment of the present invention;

is a fragmentary vertical cross-sectional e present invention a conventional shank water heater thermostat;

FIGURE 11 is a fragmentary vertical cross-sectional view of another embodiment of the present invention enlarged perspective view of a dea conventional shank assembly of a hot water heater thermostat.

of being carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring to the drawings, 1 a hot water heater 1 which utilizes the present invention. This hot water heater 1 comprises an outer casing 2 and an inner cylindrical wall 3. Insulation 4 is inserted between the casing 2 and the inner wall 3. This structure is mounted upon a base 5 which has a gas burner 6 mounted therein under the lower portion of the lower wall 7. Any other suitable combustible or electrical source of heat may be utilized. In the present embodiment, the gas burner 6 is of a conventional type in which the gas supply induces primary air to a venturi. Air and gas pass into a plenum from which a mixture is emitted through suitable openings in the burner 6, mixed with secondary air and then burned. Adjacent the openings in the burner is a pilot light burner 8. Both the pilot burner 8 and the gas burner 6 are operatively associated with a control 11 by means of gas lines 9 and 10. The control 11 has included therein a protuberance which is a thermostatic sensing element 12 commonly known in the industry as a rod and tube.

Referring now to FIGURE 4, an opening 14 in the wall of the tank 3 is provided with nut 16 secured thereto by any suitable means such as brazing or welding. An assembly shank 18 has one end threaded into the nut 16 while its opposite end projects inside the tank and a cen tral bore 20 in the shank 18 establishes communication between the control 11 and sensing element 12. A hollow tube 22 fabricated from a highly expansible metal such as copper, has a closed end 24 projecting into the water tank while its opposite threaded end 26 projects into the threaded central bore 20 for rigid attachment to the shank 18. A relatively non-expansible rod 28, such as Invar, is suspended within the hollow tube 22 and extends through the shank central bore 20. One end of the rod is attached to the plug 30- which is threaded within the extremity of the tube 22. The rod 28 has a longer longitudinal dimension than the tube 22 so that its exposed end abuts a lever 32 which can transpose movement of the rod to a clicker disc 34 mechanism, generally known in the art, and a valve (not shown) for controlling the flow of gas from the line to the conduit 36 which passes through the control 11. The innards of the control itself are not a part of the present invention and any well known hot water heater control may be used, such as that illustrated in the patent to Caparone et al. 2,707,078. It is understood that the mechanism within the control means actuated by the rod controls the transfer of gas to a burner for the water tank.

In operation, the rod 28 is free to move longitudinally as the tube 22 expands and contracts with temperature variations. The expansion and the contraction of the tube 22 transmitted by rod 28 under conditions of satisfaction and demand for heat in the water in which the device is mounted causes longitudinal movement of the rod 28. It applies pressure on the lever 32 to actuate a control means (not shown). As the demand for heat is satisfied, the tube 22 expands with the increased temperature of the water within the tank, allowing the free end of the rod 28 to move and release pressure on the lever 32 to thereby terminate flow of gas through the control 11.

It is quite conventional to place a plastic sleeve 38 upon the tube 22 for gas controls used. in hot water heater applications. This sleeve 38 acts as an insulator to the galvanic action on the tube 22- and generally extends along the entire length of the tube 22 extending into the interior cavity 40 of the shank 18.

Referring now to FIGURES 2-5, there is illustrated one embodiment of the present invention which is an insert 42 comprising a body portion 44, a lip 46 projecting therefrom, and a means for interlocking the insert 42 with the plastic sleeve 38 on the temperature sensing element 12.

A means for interlocking the insert 42 with the plastic there is shown in FIGURE sleeve may take the form of a return flange 48 formed on the bottom 50 of the insert 42. The passageway 52 through the bottom 50 of the insert 42 is of a size just a little larger than the diameter of the tube 22. The tapered return flange 48 forces the plastic sleeve 38 to ride up the flange and interlock the insert 42 with the plastic tube without an additional fastening device. While the particular return flange 48 has a tapered portion thereon, it is within the present invention to use a return flange which has a portion parallel to the length of the tube which would serve to interlock the plastic sleeve with the insert and still perform the same function.

The shank 18 is quite often constructed in many sizes and shapes and the body portion 44 of the insert 42 may extend the entire depth of the cavity 40 as shown in FIG- URES 4 and 5, or conversely it may extend only a short distance within the cavity if this is desirable. The lip 46 covers the land 47 on the shank 18 and this lip helps limit the insertion of the insert within the shank cavity.

In assembly, the insert 42 is inserted within the shank cavity 40 until the lip 46 abuts the shank land 47 There after the plastic sleeve 38 is subjected to air pressure to increase its diameter and is forced over the tube 22 until the edge of the sleeve 38 contacts the tapered return flange 48 of the insert 42. Upon release of the air pressure, sleeve 38 will contract to intimately engage the tube 22 and the forward portion of the sleeve 38 will engage the tapered return flange 48 to rigidly retain the insert 42 in the shank cavity 40. In this manner, the insert 42 cannot be removed unless the plastic sleeve 38 on the tube 22 is also removed.

Referring now to FIGURES 6-8, the length of the in sert 60 may be adjusted to any desired size in relation to the depth of the cavity 40 within the shank 18. In this embodiment, there is a plurality of perforations 62 in the bottom of the insert 60, which allow the water within the hot water tank 3 to pass therein and subject the entire length of the rod 22 to the changes in temperature of the water. In cases where the depth of the shank cavity 40 is three or four inches deep, it is advantageous to have the entire length of the rod in contact with the water, thereby rendering the entire length of the rod and tube temperature sensor effective. The size of the orifices is kept to a minimum which keeps the current density also to a minimum.

Another embodiment of the present invention is illustrated in FIGURE 9 wherein the insert 70 has basically the same configuration as shown in FIGURES 2-8. A return flange 72 is formed at the bottom 74 of the cupshaped body portion 76 and extends substantially parallel to the tube 22. Plastic sleeve 38 is expanded as it is slid over the tube 22 and extends over the return flange 72 to interlock the insert 70 upon the shank 18.

Another embodiment of the present invention is illustrated in FIGURE 10, wherein the insert 80 is quite similar in configuration to that illustrated in FIGURES 2-5 with the exception of the lip 82. In this embodiment, the lip 82 has a skirt 84 formed thereon which extends Within a groove 86 formed in the shank 18. This arrangement provides a definite position for the. insert 80 and protects the lip 82 of the insert from being pried away from the shank 18.

Still another embodiment is illustrated in FIGURE 11, wherein the insert 85 fits within the cavity 40 of the shank 18. The insert bottom 86 merely contacts the tube 22 without having a tapered return flange portion as shown. on FIGURES 9 and 10. The plastic sleeve 38 on the tube 22 extends within the shank cavity 40 and abutsthe bottom portion of the insert for locking purposes, The lip 87 at the top portion of the insert 85 has a return flange 88 and a locking rim 89 engaging an annular groove 90 formed within the shank 18. This lip 87 and locking rim 89 interlock the insert 85 to the shank 18 and prevent accidental removal- The plastic material used to fabricate the insert may be polypropylene '5 which is flexible enough to allow the rim 89 to snap within the groove 90 without cracking or deforming the insert 85.

Another embodiment is illustrated in FIGURE 12 wherein the general configuration of the insert 92 is quite similar to the inserts illustrated in FIGURES 2-6 and 9. The body 93 and lip 94 are quite similar to the insert illustrated in FIGURE 6 with the exception that the inclined portion 95 extends from the tube 22 directly to the body portion 93 and somewhat simplifies the construction of the insert. A plastic sleeve 38 rides up the inclined portion 93 during assembly and locks the insert 92 within the shank cavity 40.

While a substantial number of means for locking the insert with the plastic sleeve used on the thermostat have been illustrated, it is understood that the invention is not limited to these particular embodiments since only these preferred embodiments have been illustrated and others may be devised and that the invention is not limited by these embodiments thereto, since it may be otherwise embodied within the scope of the following claims.

I claim:

1. In combination, a thermostat and a mounting assembly for a water heater having a mounting aperture,

said mounting assembly comprising a metallic shank adapted to be rigidly fastened to the water heater,

a center bore opening into a cylindrical cavity at one end of said shank, 1 said thermostat being formed of metal dissimilar to said metallic shank and comprising a rod disposed within a hollow tube and spaced from the inner wall thereof, said hollow tube having a closed end adapted to project into the water heater and an open end secured within said center bore,

an insulating sleeve covering said tube between said cavity and said closed end of the tube,

the improvement comprising an insert having a tubular body with lip means at one end and flange means at the opposite end,

said lip means abutting the shank surface adjacent to said cavity to position said body within said cavity, and

said flange means being engaged by said insulating sleeve to retain said insert within said cavity.

2. The invention as defined in claim 1 wherein one end of said insulating sleeve has tapered means thereon for facilitating the engagement of said flange means and said sleeve.

3. The invention as defined in claim 1 wherein said flange means includes an annulus shaped member, the interior diameter of the annulus being slightly greater than the diameter of said hollow tube and the exterior diameter of the annulus 'being slightly smaller than the diameter of the cylindrical cavity in said shank.

4. The invention as defined in claim 3 wherein said flange means further includes a tapered segment extending along said tube for a short distance toward the open end of said cavity, said tapered segment facilitating the engagement of said flange means and said sleeve.

5. The invention as defined in claim 1 wherein an annular groove is formed in the shank end surface adjacent to said cavity, and said lip means includes a skirt which is seated within the groove.

6. The combination as defined in claim 1 cavity in said shank has a depth dimension the length of the tubular body of the insert,

wherein the References Cited by the Examiner UNITED STATES PATENTS 2,954,696 10/1960 Jackson 73362 3,117,205 l/1964 Adams 200137 LARAMIE E. ASKIN, Primary Examiner. 

1. IN COMBINATION, A THERMOSTAT AND A MOUNTING ASSEMBLY FOR A WATER HEATER HAVING A MOUNTING APERTURE, SAID MOUNTING ASSEMBLY COMPRISING A METALLIC SHANK ADAPTED TO BE RIGIDLY FASTENED TO THE WATER HEATER, A CENTER BORE OPENING INTO A CYLINDRICAL CAVITY AT ONE END OF SAID SHANK, SAID THERMOSTAT BEING FORMED OF METAL DISSIMILAR TO SAID METALLIC SHANK AND COMPRISING A ROD DISPOSED WITHIN A HOLLOW TUBE AND SPACED FROM THE INNER WALL THEREOF, SAID HOLLOW TUBE HAVING A CLOSED END ADAPTED TO PROJECT INTO THE WATER HEATER AND AN OPEN END SECURED WITHIN SAID CENTER BORE, AN INSULATING SLEEVE COVERING SAID TUBE BETWEEN SAID CAVITY AND SAID CLOSED END OF THE TUBE, THE IMPROVEMENT COMPRISING AN INSERT HAVING A TUBULAR BODY WITH LIP MEANS AT ONE END AND FLANGE MEANS AT THE OPPOSITE END, SAID LIP MEANS ABUTTING THE SHANK SURFACE ADJACENT TO SAID CAVITY TO POSITION SAID BODY WITHIN SAID CAVITY, AND SAID FLANGE MEANS BEING ENGAGED BY SAID INSULATING SLEEVE TO RETAIN SAID INSERT WITHIN SAID CAVITY. 